Insulin and Glucose Effects on Glucose Metabolism in Pregnant and Nonpregnant Ewes

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Abstract
The effects of 1) a rapid injection of insulin (4.4 1U) into nonpregnant ewes, 2) a continuous infusion of insulin (.14 IU/min) into pregnant and nonpregnant ewes and 3) a continuous infusion of glucose (1.2 mg/kg body weight/min) into pregnant ewes on in vivo gluconeogenesis and glucose uptake by the gravid uterus were studied; a primed continuous infusion of U-14C-glucose was used. When glucose was infused at 57% of the endogenous rate of glucose appearance, endogenous glucose production declined to about 67% of the control rate. The response of pregnant and nonpregnant ewes to a continuous insulin infusion was similar. A rapid injection of insulin into nonpregnant ewes produced an immediate increase in the rates of glucose clearance and glucose disappearance. Plasma insulin concentrations returned to control levels within 60 min and had a calculated half life of 7.7 ± 1.1 min. After 60 min of insulin infusion, plasma glucose had declined to 39 to 49% of the control level, and rates of glucose appearance and disappearance decreased by 11 to 27%. Uterine glucose uptake in pregnant ewes decreased from a control rate of 21.0 ± 5.9 to 5.3 ± 3.6 mg/kg fetus/min after insulin infusion. In pregnant ewes with 1, 2 or 3 fetuses at 109 ± 1.5 days of gestation, glucose uptake by the uterus and its contents accounted for 42.6% of total glucose turnover. Uterine glucose uptake tended to increase with an increasing number of fetuses and averaged 18 ± .1 mg/kg fetus/min. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science.